Class 8th Science Force and Pressure

Class 8 Science - Force and Pressure

1. Give two examples each of situations in which you push or pull to change the state of motion of objects.

Push examples:

• Pushing a swing to make it move back and forth.
• Pushing a trolley to start it moving.

Pull examples:

• Pulling a door to open or close it.
• Pulling a toy car with a string to move it forward.

2. Give two examples of situations in which applied force causes a change in the shape of an object.

• Pressing a rubber ball changes its shape temporarily.
• Stretching a rubber band makes it longer and thinner.

3. Fill in the blanks in the following statements:

• (a) To draw water from a well we have to pull at the rope.
• (b) A charged body attracts an uncharged body towards it.
• (c) To move a loaded trolley we have to push or pull it.
• (d) The north pole of a magnet repels the north pole of another magnet.

4. An archer stretches her bow... Fill up the gaps using the correct terms:

• (a) The force causes a change in the shape of the bow.
• (b) It is an example of a muscular force.
• (c) It is a type of contact force.
• (d) The arrow is acted upon by gravity and air resistance.

5. Identify the agent and the effect of force in each case:

• (a) Hand squeezes lemon – changes shape and juice comes out.
• (b) Finger presses toothpaste tube – paste is pushed out.
• (c) Lead on spring – pulls down, spring stretches.
• (d) Athlete jumps – legs push body to move upward.

6. A blacksmith hammers a hot piece of iron while making a tool. How does the force affect the piece of iron?

The force of hammering changes the shape of hot iron, helping the blacksmith to make a useful tool.

7. An inflated balloon was pressed against a wall... What might be responsible for the attraction?

Rubbing the balloon creates static electricity, which causes attraction between the balloon and the wall due to electrostatic force.

8. Name the forces acting on a plastic bucket with water held above ground in your hand. Why does it fall?

Gravity pulls the bucket downward. The upward force from your hand keeps it in place. If released, gravity makes it fall.

9. A rocket is launched to send a satellite into orbit. Name the force used to do this.

The rocket uses the force of burning fuel to push down, which creates an upward thrust that launches it into space.

10. We press the bulb of a dropper to let out air. What causes water to fill in?

Once we release the bulb, atmospheric pressure pushes water into the dropper due to lower pressure inside the tube.

MCQ Answer: (d) atmospheric pressure